Fluid circulating system



March 5, 1940. 5, cou -r s r AL 2,192,727

FLUID CIRCULATING SYSTEM Filed March 15, 1957 2 Sheets-Sheet 1 Gas pressure (firs! sue/me) Modify/rig appeal/a5 appara/os I 60:; pressure (Jen-and ourcep appara/u s Snoentors Sfaor/ 6? (barf/ls %//er' I (oar/1L5 March 5, 1940. s A om-HS ET AL 2,192,727

FLUID CIRCULATING SYSTEM Filed March 15,, 1957 2 Sheets-Sheet 2 2 Zhwenfors 674102? 19. (barf/ls Wa/fer f. Cour/is Patented Mar. 5, 1940 NITED STATES 2,192,721 FLUID CIRCULATING SYSTEM Stuart A. Courtis and Walter F. Courtis, Detroit, Mich.

Application March 15,

'7 Claims.

The present invention relates to a system for circulating fluids and has for its primary object to do away with the use of pumps, injectors and other such mechanical contrivances which are t ordinarily used for this purpose.

Another object of the invention is to provide a fluid circulating system, embodying an arrangement of interconnected tanks containing a fluid and means for supplying fluid of a different density thereto under pressure to circulate the first fluid from one set of tanks to another, the system also embodying automatic means which functions when the fluid has been circulated from one set of tanks to another for re- 15 versing the order of connections for the purpose of returning the fluid to the tanks from which it was first removed. The circulated fluid, for example, may be water, and the fluid which causes the circulation may, for examplabe steam or air.

Another object of the invention is to provide a fluid circulating system utilizing fluids of different density, such as a liquid and a gas or vapor under pressure for circulating the liquid 25 from one set of tanks to a second set and during such circulation passing the liquid through a modifying apparatus, such as a heat exchanger. The invention further aims to automatically reverse the order of connections so that the liquid is returned to the first mentioned tanks, the direction of its flow with respect to the modifying apparatus being the same in both cases, and the flow being controlled with respect to the individual sets of tanks whereby it is constant.

A still further object of the invention is to provide a fluid circulating system of the character above referred to wherein two sources of gas or vapor pressure are used, the first source being a comparatively low pressure and being utilized to charge containers with liquid, and the second source being at comparatively high pressure and being adapted to circulate the liquid from the charged containers through a modifying apparatus.

45 With the above and other ends in view the invention is more fully disclosed with reference to the accompanying drawings, in which:

Figure 1 is a diagram of the circulating systems;

Figs. 2 and 3 are fragmental diagrams illustrating different operative positions, and

Fig. 4 is a fragmental diagram Like characters of reference are employed throughout to designate corresponding parts.

The numerals l and 2 designate tanks adapted 1937, Serial No. 130,946

for the reception of liquid. A pressure supply manifold 3, having an inlet 4 adapted to be connected to a gas or vapor pressure source (not shown) and hereinafter referred to as the first gas pressure source, is and 2, by branch pipe lines 5 and 6 respectively. As may be seen more clearly in Figs. 2 and 3, a valve 1 is mounted in the branch pipe line 5 and has electromagnets 8 and 9 operatively con-. nected thereto. ergization thereof functions to open the valve 1 and the electromagnet 9 functions to close the valve, upon energization thereof. The branch pipe line 6 has a similar valve and electromagnets 2| and 22 are operatively connected thereto, the magnet 21 being adapted upon energization thereof to open the valve and the magnet 22, upon energization thereof, being adapted to close the valve.

A pressure exhaust manifold l0 has branch 20' pipe lines H and 12 connected to the tanks l and 2 respectively. In the branch pipe line It is a valve 13 having an electromagnet 14 adapted upon energization thereof to open the valve, and

connected to the tanks l 6 The electromagnet 8 upon en- 10 an: electromagnet [5 adapted upon energization thereof to "close the valve. In the branch pipe line 12 is a valve l6 having an electromagnet l1 operatively connected thereto and adapted upon energization thereof to open the valve, and an electromagnet thereof to close the valve.

,The several electromagnets are operated by electric circuits having controls responsive to predetermined changes in the level of liquid in the container I. I5 and are in the circuit 23 having a source 24 of E. M. F. and a switch 25 adapted to close the circuit and energize the same. This condition is shown in Fig. 2 wherein the circuit 23 is closed, the electromagnets 8, energized, thus closing valves l3 and 20 and opening valves 1 and Hi. The other electromagnets 9, 2!, l4 and. I8 are in the circuit 26 having a source 21 of E. M. F. and a switch 28 adapted to close the circuit when the tank I is lowered to that indicated in Fig. 3. When the liquid level reaches approximately the position shown in Fig. 3 the switch 28 closes the circuit 26 (the circuit 23 being open at this time), energizes the electromagnets (9, 2|, to open valves Referring again to outlet pipe lines 30 into a conduit 32;

I3 and 20 and close valves 1 and Fig. 1, tanks I and 2 have and 3| respectively, opening Check valves 33 and 34 are l8 adapted upon energization 30 That is, the electromagnets 8, 22, 35

22, i5 and I1 liquid level in the I4 and I8) provided in the pipe lines 30 and 3| which funca check valve Ma therein, to the tank 211 by the tion to prevent the flow of liquid from the .conpipe line 42a having a check Va ve a therein. duit 32 to the tanks 1 and 2 and to permit the o he t nk lb by he pip in tflb h v n the flow of liquid from the tanks I and 2 to the check valve tlb therein, to the tank 21) by the conduit. Similar sets of tanks la and 2a, lb and p p n having h ch k v v 3 therein, 5 2b, and lo and 2c are provided and are connected to the tank by the p p e 6 v ng h to the manifolds 3 and ill and to the conduit 32 Check Valve MC therein, d t e a 6' by in the same manner as the tanks l and 2. That the p line having the ck a e 30 is, the tank la is connected to the pressure supthereinply manifold 3 by a b a pipe line having a The numerals 4 3 and d5 designate, respectively, 10 valv 11 th i t th exhaust manifold m by a pair of individual tanks. A pressure manifold the branch pipe line Ha having the valve l3a 46! Connected by a pipe line m to a source of th i and t t conduit 32 by a pipe line 39 pressure (not shown), hereinafter termed the having h k valve 33,; therein The tank 2 second source, has a manual valve 48 therein. i connected t t manifold 3 by a branch pipe The manifold 36 is also connected to the presline 83a having a valve a therein, to the mani- Sure manifold 3 by a pipe line 3 having fold it by a branch pipe line l2a having a valve Valve 50 therein The mamfold I611 therein, and to the conduit 32 by a pipe line nect'ed t0 the k 64 by a branch pipe line 5! 3m having a check valve 34a therein. The tank havmg Valve thereu} and the tank l b is connected to the manifold 3 by a branch by branch f line hat/mg a a v M 20 pipe lin having a Valve therein, to the therein, both valves 52 and 54 being electrically manifold Ni by a branch pipe line llb having a operated as i heremafter, appear An exhaust valve I311 therein, and to the conduit 32 by a mamfm 55 connected the tank M pipe line 30b having a check valve 331) therein. branch plpe mm 56 having a W therem The tank 2b is connected to the manifold 3 by a to the n as y branch plpe line 58 a branch pipe line 62) having a valve 2% therein, g Valve 5 therem the Valves 5 and 59 also to the manifold is by a branch pipe line IZb bemg Operated having a valve 562) therein, and to the conduit Referrmg to F Yalve has an 816C 32 by a pipe line 35b having a check Valve 34b tromagnet ti) connected thereto and adapted 1 upon energizatlon thereof to open the valve, and

an electromagnet (it, connected thereto, which is adapted upon energization thereof to close the valve. The valve 55 has connected thereto an electromagnet 62 which is adapted upon energization'thereof to open the valve, and an electromagnet 63 which is adapted, when energized to close the valve. Connected to the valve 5'! is an electromagnet 64 adapted, when energized, to open the valve, and an. electromagnet 65 which is adapted when energized, to close the valve.

branch pipe line 1120 having a valve I60 therein, and to the conduit 32 by a pipe line 3Ie having a check valve 340 therein. U s

It becomes obvious, from the foregoing, that g g g g i 22 :3 fgggfigxg g gii the tanks ta, 2a, lb, 2b, to and 2c and the pipe mg the same 5 lines and valve arrangements relating thereto The electro'maonets 3g 65 56 and W are in the are identical to the tanks 4 and 2 and their circuit 63 having a Bourke .3 and a arrangement of the pipe lines and Valves- It will switch 79 which clos s the c cui when the liquid 46 be understood a though it is not shown, that the level in the tank :eaches 1, plane Shown in electric c1rcuits and the electromagnets above Fig 4 The electrmnagnets and 67 are descrlbed are also duplicated in order that the in 5 electric circuit s source of E valves l3a, 13b and 530 function in like manner M F 72 and a g ji to close to the valve E3 the valves Ia, 1b and 1c inlike cilicui't to energize f fi 52 M and 61 manner to the valve the valves 26a, 20b and when the liquid lpvel in 2 lowerc to Zilc in l ke manner to the valve 20, and the valves the plang of the smch U 16a, 86b and We in like manner to the valve I6. A conduit M having a manual Valve 15 thmein As illustrated how ver, the liquid levels in the is connected the pipe 11118135, several tanks 5 M and 2a lb and 2b modifyin apparatus 35 and is connected to the and 2c are not un1form, although they contain tank 45 Check Valve iq vfaced in the like amounts Of Due to condition 'na the t fu 610 t the valves relat ng to the difierent sets of tanks, rmit th n f L T I although operated in like mannei do not operpe 6 Ow O mm b 6 uft the tank While preventing the flow of liquid Irozn the ate at the same time. tank to the 00nd ui. i lin i a": The Condult 32 15 connected Wlth a modlfying check valve 78 the;ein e i t 2;1ds f ron i t a nli apparatus diagrammatically illustrated at 35, and 45 to the modifying aparaws the modl-fying a pipe 8 3 having a manual Valve 37 connects apparatus 79 being connected b pipe line 80 to the modlfymg apparatus 35 with modifying apthe tank 44. The pipe line at has a check valve p at s A condult 39 18 Connected to the 8| which prevents the flow of liquid from the modlfylng apparatus and extends adjacent the tank 44 thereinto. A conduit 82 is connected to tanks l and 2, la and 2a, l b and 2b and I0 and 2c. the tank 35 by a branch line 33 having a check A pipe line d8 connects the conduit 39 with the valve 84 therein, the conduit 82 also having a tank l and has a check valve 4! therein which check valve 85 and a manual valve 8%, and being prevents liquid flow from the tank l to the conconnected to the pipe line 36 adjacent the modi- 70 duit. A pipe line 32 connects the conduit 39 with fying apparatus 38. the tank 2 and has a check valve Q3 therein which A set of tanks Ma and 45a are provided and prevents the flow of liquid from the tank 2 to the are similar to the tanks 44 and 15 in their assoconduit 39. Similarly, the conduit 39 is conciation with the system, and although it is not nected to the tank la by a pipe line 40a having illustrated, it will be understood that the valves 7 to be described are operated by circuits and electromagnets identical to those operating the valves 52, 54, 5'! and 59.

As will be seen upon reference to Fig. 1, the tank 44a is connected to the pressure manifold 45 by a branch pipe line 5| a having a valve 52a therein and to the exhaust manifold 55 by a branch pipe line 55a having a valve 51a therein. The tank Me has a branch pipe line 80a, connected to the pipe line 89 and having a check valve Bla therein, and is also connected by the branch pipe line 83a to the conduit 82. The branch pipe line 83a has a check valve 84a therein. The tank 45a is connected to the pressure manifold 45 by a branch pipe line 53a having an electromagnetic valve 540. therein, and tothe exhaust manifold 55 by a branch pipe line 58a having an electromagnetic valve 59a therein. The conduit 14 has a branch pipe 14a connected to the tank 45a and provided with a check valve 160. and the pipe H has a branch Ila. connected to the tank 45a. The branch pipe Ila has a check valve i811. therein.

In describing the first function of the present system it will be assumed that the manual valve 31! is open and the manual valves 15 and 86 are closed. With the several electromagnetic valves 1, l3, l5 and 2D in the position shown in Fig. 2, gas or vapor, under pressure, is admitted to the tank I, and inasmuch as valve I3 is closed at this time, the gas forces the liquid from the tank I. The liquid so expelled circulates through the branch pipe 30 and conduit 32 to the modifying apparatus 35, through the pipe line 36 to the modifying apparatus 38 and into the conduit 39. The valve 2|] is, at this stage, closed and the valve I5 is open. The gas may exhaust from the tank 2, therefore, and the liquid circulates from the conduit 39 through the branch pipe 42 into the tank 2. When the tank I is emptied and the tank 2 is filled, as shown in Fig. 3, the pressure valve 1 closes and the exhaust valve l3 opens. Simultaneously, the pressure valve 20 opens and the exhaust valve l6 closes, and the liquid is forced from the tank 2 and circulates through the conduit 32, the modifying apparatus 35, the pipe line 36 and the modifying apparatus 38 to the conduit 39. Inasmuch as the gas may exhaust from the tank I through the valve [3, the liquid flows from the conduit 39 into the tank I. It becomes apparent, therefore, that the liquid is circulated from one container to the other and that the order of connections is such as to provide a one directional flow.

When the valves |3a and 20a are closed and the valves la and Ilia open, liquid is forced from the tank la into the conduit 32, and flows from the conduit 39 into the tank 2a. When the tank 20. is filled the order of the valves is reversed, and the liquid flows from the tank 2a into the conduit 32 and from the conduit 39 into the tank la. When the valves I31) and 2012 are closed and the valves la and Ilia open, liquid is forced from. the tank lb into the conduit 32 and fiows from the conduit 39 into the tank 2b until such time as the latter is filled and the valve order reversed. The valves 13c, 200, 1c and IE0 function in like manner with respect to the tanks I c and 2c.

The order of functioning of the valves relating to the several sets of tanks is such that no two sets of valves change positions at the same time. That is, at the time the valves 1, I3, [6 and 20 change their position from that shown in Fig. 2

to that shown in Fig. 3 the other tanks 1a and- 2a, lb and 2b and lo and 20 will be filling and emptying, as the case may be. The same condition is present with respect to the valves la, l3a, Mia and 29a, valves 117, I31), I61) and 20b and valves 10, I30, I and 20c. With this relationship the liquid fiows continuously, due to the fact that when the fiow is interrupted momentarily with respect to any pair of tanks liquid flow with respect to the remaining sets of tanks is taking place. The flow is indicated in Fig. 1 by full line and dotted line arrows, the full line arrows indicating the flow when the valves are positioned as shown in Fig. 2, and the dotted line arrows indicating the flow which takes place when the valves are in the position shown in Fig. 3.

During the function of the second stage of the system the valve 31 is closed and the valves 15 and 86 are opened, and the liquid, after leaving the modifying apparatus 35, flows through the conduit 14 and its branch pipe line 14a. and into the tanks 45 and 45a when the valves 59 and 59a. are open, as shown in Fig. 4. When the valves 59 and 59a are open, the valves 54 and 54a. are closed, the valves 51 and 51a which relate to the tanks 44 and 44a are closed and the valves 52 and 52a. are open Therefore, while the liquid enters the tanks 45 and 45a liquid is discharged from the tanks 44 and 44a, the manner in which the tanks 44 and 44a were previously filled being described later.

With the valves in the position shown in Fig. 4, liquid flows from the tank 44 through the branch pipe 83, while other liquid flows into the tank 45, until the switch 12 is actuated, at which time the valves 51 and 54 are opened by their respective electromagnets while valves 52 and 59 are closed. Gas pressure is thus admitted from the second source 41 and forces the liquid from the tank 45 through the pipe line H to the modifying apparatus 19, and through the pipe line 89 to the tank 44. When the tank 44 is filled the switch 10 is closed and the order of the valves is again reversed so that the liquid is forced from the tank 44 under pressure from the second source 41, through the branch line 83 and conduit 82 to the modifying apparatus 38, from which the circuit is the same as above described.

Although the controls are not shown in detail, it will be readily understood by those skilled in the art, that the valves 52a, 54a, 51a and 59a function in like manner to the valves 52, 54', 51 and 59 respectively. That is, when the valves 54a and 51a are open and valves 52a and 59a are closed liquid flows from the tank 45a through the branch pipe 11a and the pipe line 11 to the modifying apparatus 19, from which it fiows through the conduit 80 and branch pipe line 80a to the tank 44a. When the valves 54a and 51a are closed and valves 52a and 59a are open the liquid fiows from the tank 44a through the branch pipe 83:: to the conduit 82. It is preferred that while the tank 45 is being filled, as above described, the liquid will be discharged from the tank 45a, and while the tank 45a is filling it will discharge from the tank 45.

From the foregoing, it becomes apparent that the liquid is circulated with respect to the first battery of tanks by pressure from the first source 4 and that the liquid so circulated is circulated through the modifying apparatus 19 by pressure from the second source 41. By closing the valve 48 and opening the valve 50 the liquid may be circulated with respect to the tanks 44, 45, 44a. and 451: by pressure from the first source supplied to the manifold 46 through the pipe line 49.

As a matter of convenience in describing and claiming the present invention the'pressure supplying fiuid is referred to as a gas or vapor, while the circulated fluid is referred .to as liquid. It

1 will be understood, however, that the system may beoperated where both fluids are of liquid form or where both fluids are of vaporous or gaseous form, provided in both cases that the density characteristics vary to such an extent that they do not mix appreciably. Inasmuch as liquid and a gas or vapor provide common examples of fluids of different densities such terms have been used in describing and claiming. the invention.

To illustrate the utility of the present device let it be assumed that the whole diagram represents an apparatus for collecting and utilizing radiant energy from a solar source. In such an apparatus, energy in the form of heat is collected from the sun's rays by a liquid and is subsequently extracted from the liquid for the performances of some useful functions. Solar heaters are well known to the public and for this reason a detailed showing of such a heater is deemed unnecessary to an understanding of the invention. It is also known that-different liquids are used in such heaters, and they are sometimes opaque and of quite viscous nature.

In such a heater, the modifying apparatus 35 represents the absorbing agency, or in other words, the liquid in the modifying apparatus is subjected to concentrated suns rays and is heated. The liquid would be driven in a steady stream from the cylinders i and 2, la and 2c, lb and 21), lo and 2c, acting alternately in pairs as described above. The liquid would pass slowly in thin tub-es and under low pressure in order that it might be heated to a high temperature by absorbed solar energy. By the valve l5'the heated liquid is diverted to the tanks it, ill, Mia and 55a and is circulated from them under high pressure through the modifying apparatus l9 which would be a heat exchanger. The heat exchanger, as represented by the modifying apparatus l9 would include sma thin tubes and the liquid would be moved very rapidly to decrease the skin effect in the tubing and to minimize the losses by radiation. In such a case, the heat from the circulated liquid is utilized to generate steam for example.

From the modifying apparatus or heat exchanger 59 the liquid, with part of the heat extracted therefrom, is circulated as above described to the modifying apparatus 38, which comprises a pre-heater for the water which is converted into steam in the heat exchanger It. The water circuit is not shown on the drawings.

The gaseous medium for circulating the energy collecting liquid might, for example, be compressed air supplied from an outside source.

Although a specific embodiment of the in vention has been illustrated and described it will be understood that various changes may be made within the scope of the appended claims without departing from the spirit of the invention, and such changes are contemplated.

What we claim is:

1. In a system of the character described, a plurality of pairs of tanks, eachtank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, the pressure inlet and outlet valves of one tank of a pair are respectively open and, closed when the pressure inlet and outletvalves of the other tank of the pair are respectively closed and open, each tank having check valve controlled liquid inlets and outlets, a modifying apparatus, means connecting the liquid outlets of all tanks to said modifying apparatus, means connecting the liquid inlets of all tanks to said modifying apparatus, and means individual to each pair of tanks for automatically operating the valves of said gas pressure inlets and outlets of each pair of tanks simultaneously, for alternately supplying gas pressure thereto and exhausting it therefrom to alternately empty said tanks into the first named means and fill said tanks from the second named means, the valves of any pair of tanks being operated at a diiferent time than the time of operation of the valves of any other pair of tanks.

2. In a system of the character described, a

lurality of pairs of tanks, each tank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, the pressure inlet and outlet valves of one tank of a pair are respectively open and closed when the pressure inlet and outlet valves of the other tank of the pair are respectively closed and open, each tank having check valve controlled liquid inlets and outlets, a modifying apparatus, means connecting the liquid outlets of all tanks to said modifying apparatus, means connecting the liquid inlets of all tanks to said modifying apparatus, means individual to each pair of tanks for operating the valves of said gas pressure inlets and outlets of each pair of tanks simultaneously, for alternately supplying gas pressure thereto and exhausting it therefrom to alternately empty said tanks into the first named means and fill said tanks from the second named means, the valves of any pair of tanks being operated at a different time than the time of operation of the valves of any other pair of tanks, and means responsive to predetermined changes in the liquid level in one tank for automatically operating said last named means.

3. In a system of the character described, a pair of tanks, each tank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, said inlets being connected to means for supplying gas pressure thereto, each tank having a check valve controlled outlet connected to a common conduit and a check valve controlled inlet connected to a second common conduit, means for operating said valve controlled gas inlets and outlets alternately whereby gas pressure exhausts liquid from one tank into the first conduit and exhausts from the other tank whereby liquid flows from the second conduit thereinto, a second pair of tanks, each tank of said second pair having a valve controlled gas pressure inlet connected to a second means forsupplying gas pressure and a valve controlled outlet, each tank of the second pair having check valve controlled liquid inlets and outlets, means connecting the liquid inlet of the first tank of said second pair to said first conduit, a modifying apparatus, means connecting the liquid outlet of said first tank to the inlet of said modifying apparatus, means connecting the outlet of said modifying apparatus to the liquid inlet of the second tank of said second pair, means connecting the outlet of said second tank to said second conduit, and means for operating said valve controlled inlets to alternately supply gas pressure from the second source to the tanks of said second pair and for exhausting such gas pressure therefrom.

l. In a system of the character described, a pair of tanks, each tank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, said inlets being connected to means for supplying gas pressure thereto, each tank having a check valve controlled outlet connected to a common conduit and a check valve controlled inlet connected to asecondcommon conduit, means for operating said valve controlled gas inlets and outlets alternately whereby gas pressure exhausts liquid from one tank into the first conduit and exhausts from the other tank whereby liquid flows from the second conduit thereinto, a second pair of tanks, each tank of said second pair having a valve controlled gas pressure inlet connected to a second means for supplying gas pressure and a valve controlled outlet, each tank of the second pair having check valve controlled liquid inlets and outlets, means including a modifier connecting the liquid inlet of the first tank of said second pair to said first conduit, a modifying apparatus, means connecting the liquid outlet of said first tank to the inlet of said modifying apparatus, means connecting the outlet of said modifying apparatus to the liquid inlet of the second tank of said second pair, means connecting the outlet of said second tank to said second conduit, and means for operating said valve controlled inlets to alternately supply gas pressure from the second source to the tanks of said second pair and for exhausting such gas pressure therefrom.

5. In a system of the character described, a pair of tanks, each tank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, said inlets being connected to means for supplying gas pressure thereto, each tank having a check valve controlled outlet connected to a common conduit and a check valve controlled inlet connected to a second common conduit, means for operating said valve controlled gas inlets and outlets alternately whereby gas pressure exhausts liquid from one tank into the first conduit and exhausts from the other tank whereby liquid flows from the second conduit thereinto, a second pair of tanks, each tank of said second pair having a valve controlled gas pressure inlet connected to a second means for supplying gas pressure and a valve controlled outlet, each tank of the second pair having check valve controlled liquid inlets and outlets, means connecting the liquid inlet of the first tank of said second pair to said first conduit, a modifying apparatus, means including a modifier connecting the liquid outlet of said first tank to the inlet of said modifying apparatus, means connecting the outlet of said modifying apparatus to the liquid inlet of the second tank of said second pair, means connecting the outlet of said second tank to said second conduit, and means for operating said valve controlled inlets to alternately supply gaspressure from the second source to the tanks of said second pair and for exhausting such gas pressure therefrom.

6. In a system of the character described, a pair of tanks, each tank having a valve controlled gas pressure inlet and a valve controlled gas pressure outlet, said inlets being connected to means for supplying gas pressure thereto, each tank having a check valve controlled outlet connected to a common conduit and a check valve controlled inlet connected to a second common conduit, means for operating said valve controlled gas inlets and outlets alternately, whereby gas pressure exhausts liquid from one tank into the first conduit and exhausts from the other tank whereby liquid fiows from the second conduit thereinto, a second pair of tanks, each tank of said second pair having a valve controlled gas pressure inlet connected to a second means for supplying gas pressure and a valve controlled outlet, each tank of the second pair having check valve controlled liquid inlets and outlets, means connecting the liquid inlet of the first tank of said second pair to said first conduit, a modifying apparatus, means including a modifier connecting the liquid outlet of said first tank to the inlet of said modifying apparatus, means connecting the outlet of said modifying apparatus to the liquid inlet of the second tank of said second pair, means connecting the outlet of said second tank to said second conduit, means for operating said valve controlled inlets to alternately supply gas pressure from the second source to the tanks of said second pair and for exhausting such gas pressure therefrom, and means for actuating said last named means in response to predetermined changes in the liquid level in one of the second pair of tanks.

'7. In a system of the character described, a pair of tanks, each of said tanks having an inlet and an outlet for fiuid and having a second inlet and a second outlet for other fluid under pressure, a modifying apparatus, means connecting said first-named outlets of each tank to said modifying apparatus, means connecting said first-named inlets of the tanks to said modifying apparatus valve means controlling said second named inlets, valve means controlling said second-named outlets, and means to control operation of said valves and operable in response to predetermined changes of a physical characteristic of the firstmentioned fluid in one of said pair of tanks said inlet and outlet Valves of one tank of a pair of tanks being respectively opened and closed when the inlet and outlet valves of the other tank of the pair of tanks are respectively closed and opened.

STUART A. COURTIS. WALTER F. COURTIS. 

